import java.util.*;


/**
 * Represents a collection of Files; how many it can hold is limited by its capacity.
 */
public class Disk implements Comparable<Disk>
{    
    private int myId;
    private int mySize;
    private int myCapacity;
    private List<Integer> myFiles;


    /**
     * Create an empty Disk.
     */
    public Disk ()
    {
        mySize = 0;
        myCapacity = 1000000;
        myFiles = new ArrayList<Integer>();
    }


    /**
     * Create an empty Disk with the given ID.
     */
    public Disk (int id)
    {
        this();
        myId = id;
    }


    /**
     * @return amount of free space available on this disk
     */
    public int freeSpace ()
    {
        return myCapacity - mySize;
    }


    /**
     * Adds the given file to this disk.
     * 
     * No error checking is done to ensure the file can fit on this disk.
     * 
     * @param filesize  size of file to add to this disk
     */
    public void add (int filesize)
    {
        myFiles.add(filesize);
        mySize += filesize;
    }

    /**
     * Converts this disk's information to a string.
     */
    public String toString ()
    {
        String result = myId + "\t" + freeSpace() + ":\t";
        for (int k = 0; k < myFiles.size(); k++)
        {
            result += " " + myFiles.get(k);
        }
        return result;
    }


    /**
     * Check if this disk's information is the same as the given disk's.
     * 
     * Note, currently only equality is based only on their ID.
     * 
     * @param other disk to compare to this disk
     * @return true iff their values match
     */
    public boolean equals (Disk other)
    {
        if (other != null) return myId == other.myId;
        else               return false;
    }


    /**
     * Compare this disk's information to the given disk's for ordering.
     * 
     * Note, currently only equality is based only on their free space.
     * 
     * @param other disk to compare to this disk
     * @return positive if this disk is greater than the given disk,
     *         zero if they are equal, and
     *         negative if this disk is less than the given disk
     */
    public int compareTo (Disk other)
    {
        if (other != null)
        {
            int result = other.freeSpace() - freeSpace();
            if (result == 0) return myId - other.myId;
            else             return result;
        }
        else
        {
            return -1;
        }
    }
}
